The best choice to convince your friend that changing the order of the numbers being multiplied is valid is:
The Commutative Property of Multiplication says that changing the order in which you multiply the factors does not change the answer; a×b=b×a.
This property ensures that no matter how you rearrange the factors in a multiplication problem, the result remains the same. Therefore, your method of changing the order can lead to a simpler calculation without affecting the outcome.